CC rollerblading calories burned...

ok so i was looking at how many calories were burned doing rollerskating and rollerblading and it said for an hour rollerskating= 385 cph but then rollerblading said 661 calories per hour. is there a certain MPH for the rollerblading to be twice as much? how is this?

 I rollerbladed for about an hour back in July and only burned 380-something calories.  I wasn't just gliding along, although I wasn't racing for my life either.
http://www.calorie-count.com/forums/post/5239 1.html

I compare it to how much cals the machines in the gym say I burn: If I work up a good sweat it usually around 600 cals. Which compares pretty well with the numbers it gives here. If I rollerblade really hard (we often go on a path where there's a lot of wind, so one direction is very hard and my heart rate goes above 160) I assume I'm burning 600 cals/hour. If I just troll along I figure it's 350 or so.I used a Polar HR monitor with cal measuring for a while, and that jived with these numbers as well, both rollerblading and in the gym.